One factor no one has mentioned is "what's the cost of doing a deploy" and "what's the cost of recovering from a bad deploy". If your product is purely server-

One factor no one has mentioned is "what's the cost of doing a deploy" and "what's the cost of recovering from a bad deploy". If your product is purely server-side then both of these costs can be made small and you can perhaps release multiple times per day. If your product is a desktop app that users have to download or a mobile app that has to be certified then deploy costs are larger (esp for your users) and may be bottlenecked by some external gatekeeper. If your product is embedded software that cannot be remotely updated where you need to do a complete product recall to fix any serious bugs or pay technicians to visit each site to roll out a new version... you might want to release once every year or two with a very high quality bar.